Supported catalyst for carbon nanotube production

Abstract

The present invention is directed to the number average particle size (D MN The present invention provides a supported catalyst for producing carbon nanotubes, which includes a support having a particle size of 1.5 to 20 μm and an active component supported on the support, and which prevents aggregation between particles, allows all of the supported active components to function as effective components, and has excellent activity, thereby improving the production yield.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2020-0173605 filed on December 11, 2020, and all the contents disclosed in the literature of the Korean patent application are incorporated herein by reference in their entirety.

[0002] The present invention relates to a supported catalyst for manufacturing carbon nanotubes and a method for manufacturing carbon nanotubes using the supported catalyst.

Background Art

[0003] Carbon nanomaterials include fullerene, carbon nanotube (CNT), graphene, graphite nano plate, etc., depending on the shape of the material. Among them, a carbon nanotube is a macromolecule in which a hexagonal honeycomb-shaped graphite sheet in which one carbon atom is bonded to three other carbon atoms is wound roundly to a nano-sized diameter.

[0004] Carbon nanotubes are hollow, light, have electrical conductivity as good as copper, thermal conductivity as excellent as diamond, and tensile strength not inferior to steel. Depending on the wound shape, they may be divided into single-walled carbon nanotube (SWCNT), multi-walled carbon nanotube (MWCNT), and rope carbon nanotube.

[0005] Recently, research on carbon nanotube synthesis technology capable of synthesizing a large amount of carbon nanotubes at once has been actively conducted. In the case of the thermal chemical vapor deposition method using a fluidized bed reactor among various methods, it is particularly preferable in that a large amount of carbon nanotubes can be easily and continuously synthesized.

[0006] In the synthesis of such carbon nanotubes, when the yield of the produced carbon nanotubes increases with respect to the catalyst used, the manufacturing cost is reduced and the productivity is improved. Therefore, generally, a method of increasing the activity of the catalyst by increasing the active component supported on the carrier is applied. However, when increasing the supported amount of the active component, if more than a certain amount is supported, there is a problem that a sintering phenomenon occurs between them during the manufacturing process of the supported catalyst, and the activity of the catalyst decreases.

[0007] Therefore, there is a situation where further research is needed on a supported catalyst for manufacturing carbon nanotubes in which the supported amount of the active component is optimized and the manufacturing efficiency of carbon nanotubes can be maximized.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] The present invention is for solving the above problems, and an object thereof is to provide a supported catalyst for manufacturing carbon nanotubes that can increase the synthesis yield of carbon nanotubes by optimizing the supported efficiency of the active component and maximizing the amount of the active component supported.

Means for Solving the Problems

[0010] The present invention provides a supported catalyst for manufacturing carbon nanotubes.

[0011] (1) The present invention provides a supported catalyst for manufacturing carbon nanotubes, including a carrier having a number average particle size (D MN ) of 1.5 to 20 μm and an active component supported on the carrier.

[0012] (2) The present invention provides a supported catalyst for manufacturing carbon nanotubes, in which, in the above (1), the number average particle size of the carrier is 4.0 to 20 μm.

[0013] (3) The present invention provides a supported catalyst for manufacturing carbon nanotubes, in which, in the above (1) or (2), the number average particle size of the carrier is 4.0 to 19 μm.

[0014] (4) The present invention provides a supported catalyst for manufacturing carbon nanotubes, in which, in any one of the above (1) to (3), the active ingredient is contained in an amount of 5 to 30% by weight based on the total weight of the supported catalyst for manufacturing carbon nanotubes.

[0015] (5) The present invention provides a supported catalyst for manufacturing carbon nanotubes, in which, in any one of the above (1) to (4), the active ingredient includes a main catalyst component and a promoter component, and the molar ratio of the promoter component to the main catalyst component is 10:0.1 to 10:10.

[0016] (6) The present invention provides a supported catalyst for manufacturing carbon nanotubes, in which, in any one of the above (1) to (5), the main catalyst component is one or more selected from nickel, cobalt, and iron.

[0017] (7) The present invention provides a supported catalyst for manufacturing carbon nanotubes, in which, in any one of the above (1) to (6), the promoter component is one or more selected from molybdenum and vanadium.

[0018] (8) The present invention provides a supported catalyst for manufacturing carbon nanotubes, which is used for manufacturing bundled carbon nanotubes, in any one of the above (1) to (7).

[0019] (9) The present invention provides a method for manufacturing carbon nanotubes, comprising the steps of injecting a supported catalyst for manufacturing carbon nanotubes according to any one of (1) to (8) above into a fluidized bed reactor, and supplying a carbon source gas and a fluidizing gas to the fluidized bed reactor to react and manufacture carbon nanotubes.

[0020] (10) The present invention provides a method for manufacturing carbon nanotubes, wherein in (9) above, the carbon nanotubes are bundled carbon nanotubes.

Advantages of the Invention

[0021] The supported catalyst for manufacturing carbon nanotubes of the present invention has excellent catalytic activity by optimizing the supported amount of the active component and increasing the effective amount of the active component through the selection of the support, and thereby can increase the production amount of the manufactured carbon nanotubes compared to the input amount of the catalyst.

Embodiments for Carrying Out the Invention

[0022] Hereinafter, the present invention will be described in more detail.

[0023] The terms and words used in this specification and the claims should not be construed as being limited to the ordinary or dictionary meanings. The inventors should interpret them in accordance with the meanings and concepts consistent with the technical idea of the present invention in accordance with the principle that they can appropriately define the concept of the terms in order to explain their invention in the best way.

[0024] The term "carbon nanotube" used in the present invention is a secondary structure formed by aggregating unit bodies of carbon nanotubes so that they are entirely or partially bundled. The unit body of the carbon nanotube has a cylindrical shape with a nanosize diameter and an sp2 bonding structure, where the graphite sheet has a cylindrical shape with a nanosize diameter and an sp2 bonding structure. Here, depending on the angle and structure by which the graphite sheet is wound, it can exhibit conductor or semiconductor characteristics. The unit body of the carbon nanotube is classified into single-walled carbon nanotubes (SWCNT), double-walled carbon nanotubes (DWCNT), and multi-walled carbon nanotubes (MWCNT) according to the number of walls forming the wall, and the thinner the wall thickness, the lower the resistance.

[0025] The carbon nanotube of the present invention can include any one or two or more of single-walled, double-walled, and multi-walled carbon nanotube unit bodies.

[0026] Supported catalyst for carbon nanotube production According to an embodiment of the present invention, there is provided a supported catalyst for carbon nanotube production, including a support having a number average particle size (D MN ) of 1.5 to 20 μm and an active ingredient supported on the support.

[0027] The supported catalyst of the present invention can increase the effective amount of the supported active ingredient by selecting a support having a specific particle size, whereby the amount of carbon nanotubes produced can be greatly increased compared to the amount of catalyst used.

[0028] The supported catalyst for carbon nanotube production according to an embodiment of the present invention is particularly suitable for use in the production of bundled carbon nanotubes. The bundled carbon nanotubes refer to carbon nanotubes having a secondary shape in the form of a bundle or rope in which a plurality of carbon nanotubes are arranged or aligned in parallel in a predetermined direction. Compared with entangled carbon nanotubes having a spherical or potato-like secondary shape in which a plurality of carbon nanotubes are entangled without directionality, the bundled carbon nanotubes have higher dispersibility in a solvent and are suitable for production into a dispersion liquid. When the supported catalyst for carbon nanotube production of the present invention is used, bundled carbon nanotubes can be produced more smoothly.

[0029] Hereinafter, the supported catalyst according to an embodiment of the present invention will be described in more detail.

[0030] Support The support according to an embodiment of the present invention has a number average particle size (D MN ) of 1.5 to 20 μm. When a support having a particle size in the above range is applied, aggregation between the supported catalyst particles carrying the active ingredient can be prevented, and the effective amount among the supported amounts of the active ingredient can be maximized.

[0031] Specifically, the number average particle size of the support is 1.5 to 20 μm, preferably 4.0 to 20 μm, and more preferably 4.0 to 19.0 μm. When the number average particle size of the support is less than 1.5 μm, a phenomenon of entanglement occurs due to the aggregation force between the particles of the supported catalyst. When it is greater than 20 μm, the effective amount of the active ingredient does not increase any further, and loss of the metal used as the active ingredient may occur. Instead, the active ingredient supported in the support becomes non-uniform, resulting in an increase in production cost and a decrease in production yield. The more finely the particle size distribution is controlled within the preferred range, the more the effective amount of the active ingredient supported in the support can increase.

[0032] The particle size distribution characteristics of the carrier can be directly reflected in the supported catalyst for carbon nanotube production, and the supported catalyst having such a particle size distribution can play a significant role in improving the production yield of carbon nanotubes.

[0033] The carrier can include one or more selected from the group consisting of magnesium oxide, calcium oxide, aluminum hydroxide, zirconium oxide, and silicon oxide. Preferably, it can be aluminum hydroxide. More preferably, it can further include one or more oxides selected from the group consisting of zirconium, magnesium, and silicon in the aluminum hydroxide. When using a carrier of the above types, there are advantages in terms of excellent durability of the carrier and easy loading of the active ingredient.

[0034] The shape of the carrier is not particularly limited, but it can be spherical or potato-shaped. Further, the carrier can have a porous structure, a molecular sieve structure, a honeycomb structure, etc., so as to have a relatively high surface area per unit mass or unit volume.

[0035] Active ingredient The supported catalyst for carbon nanotube production according to an embodiment of the present invention is one in which an active ingredient is supported on a carrier, and the active ingredient can include a main catalyst component and a promoter component.

[0036] The main catalyst component can be one or more selected from nickel, cobalt, and iron, and cobalt is particularly preferred. The main catalyst component plays a role in directly lowering the activation energy of the reaction in which carbon nanotubes are synthesized from the carbon source gas and smoothing the carbon nanotube synthesis reaction. When using a main catalyst component of the above types, it is preferable in that the activity of the produced catalyst is high and the durability can be ensured to a certain level or more.

[0037] The promoter component can be one or more selected from molybdenum and vanadium, and is particularly preferably vanadium. The promoter component plays a role in further enhancing the catalytic activity of the main catalyst component. When the above-mentioned promoter component is used, it can have an excellent synergistic effect with the main catalyst component and can prevent the aggregation of the main catalyst components during the production process.

[0038] According to one embodiment of the present invention, among the supported catalysts for producing carbon nanotubes of the present invention, the catalyst component can have the composition of the following Chemical Formula 1.

[0039] [Chemical Formula 1] (Ni, Co, Fe) x (Mo, V) y

[0040] In the above formula, x is the molar ratio of the main catalyst component, y is the molar ratio of the promoter component, and the x and y are each real numbers having a range of 1 ≤ x ≤ 10 and 0.1 ≤ y ≤ 10.

[0041] Specifically, the molar ratio of the main catalyst component to the promoter component can be 10:0.1 to 10:10, preferably 10:0.5 to 10:5. When adjusting the composition of the active component to have such a molar ratio, the activity of the supported catalyst can be maintained at an excellent level, and the active components in the support can be uniformly supported without aggregation.

[0042] According to one embodiment of the present invention, the supported catalyst can contain 5 to 30% by weight of the active component, preferably 10 to 30% by weight, and more preferably 15 to 30% by weight based on its total weight. The content of the active component at this time means the effective amount of the catalyst component that substantially participates in the synthesis of carbon nanotubes. In order to have such an effective amount, a support that satisfies the above-mentioned particle size distribution, that is, a specific range of the number average particle size and the volume average particle size, needs to be applied.

[0043] Manufacturing method of the supported catalyst for producing carbon nanotubes The present invention provides a method for manufacturing a supported catalyst for manufacturing carbon nanotubes as described above. Specifically, the present invention includes a step of manufacturing a supported catalyst for manufacturing carbon nanotubes by supporting a catalyst solution on a support having a number average particle size (D MN ) of 1.5 to 20 μm and then firing at 500°C to 800°C.

[0044] As described above, the support used in the present invention has a number average particle size (D MN ) of 1.5 to 20 μm, and a support satisfying the range of the number average particle size can be obtained and used, or directly manufactured and used. In particular, after the obtained or manufactured support is separated according to particle size through a classifier, only the support satisfying the number average particle size in the above range can be taken and used.

[0045] When directly manufacturing the support, the support can be manufactured by a step of heat-treating aluminum hydroxide. Further, before performing the step of heat-treating, a step of pretreating the aluminum hydroxide (Al(OH)3) can be performed first. The pretreatment can be performed at 50°C to 150°C for 1 hour to 24 hours. When performing the pretreatment, residual solvents or impurities that may be present on the surface of aluminum hydroxide (Al(OH)3) can be removed.

[0046] The aluminum hydroxide (Al(OH)3) can have a porosity of 0.1 to 1.0 cm 3 / g and a specific surface area of less than 1 m 2 / g.

[0047] By performing the heat treatment, aluminum hydroxide is converted to produce a carrier containing 30% by weight or more of AlO(OH) and 70% by weight or less of Al(OH)3, specifically 40% by weight or more of AlO(OH) and 60% by weight or less of Al(OH)3, but no Al2O3. If the temperature is lower than the above-mentioned temperature, aluminum hydroxide will not be converted to AlO(OH), and if the temperature exceeds the above-mentioned temperature, aluminum hydroxide may be converted to produce Al2O3. The heat treatment can be carried out in an air atmosphere. On the other hand, the heat treatment step can be carried out at 250°C to 500°C, particularly specifically at 400°C to 500°C.

[0048] In the method for producing a supported catalyst for carbon nanotube production of the present invention, the catalyst solution can be a mixture containing a main catalyst precursor, a promoter precursor, and an organic acid.

[0049] The catalyst solution contains a precursor of the main catalyst component and a precursor of the promoter component to be supported, and in addition, contains an organic acid. The organic acid used in the present invention can be, for example, a polycarboxylic acid, which is a compound containing one or more carboxyl groups, has high solubility as a complexing agent, suppresses precipitation, facilitates the synthesis of the catalyst, and increases the synthesis of carbon nanotubes as an activator. The polycarboxylic acid can be one or more selected from dicarboxylic acids, tricarboxylic acids, and tetracarboxylic acids, and for example, citric acid, oxalic acid, malonic acid, succinic acid, or tartaric acid can be used.

[0050] The organic acid can be contained in an amount of 0.1 to 1.5% by weight based on the total weight of the catalyst solution. Within such a range, precipitation of the metal components of the main catalyst and the promoter in the catalyst solution does not occur, and thereafter, the generation of cracks during the firing process can also be suppressed.

[0051] Also, the molar ratio of the sum of the main catalyst precursor and the cocatalyst precursor to the organic acid can be appropriately mixed in the range of about 5:1 to 30:1. When such a molar ratio is satisfied, the bulk density of the produced carbon nanotubes can be realized at an excellent level.

[0052] The main catalyst precursor and the cocatalyst precursor can be any compound that can be converted into the main catalyst component and the cocatalyst component through the processes of drying and firing hereinafter, without particular limitation. In the case of nickel, iron, and cobalt exemplified as the preferable main catalyst components above, salts, oxides of these metal components, or compounds containing these metal components can be used as the main catalyst precursor. More specifically, substances such as Fe(NO3)2·6H2O, Fe(NO3)2·9H2O, Fe(NO3)3, Fe(OAc)2, Ni(NO3)2·6H2O, Co(NO3)2·6H2O, Co2(CO)8, [Co2(CO)6(t-BuC=CH)], and Co(OAc)2 can be used. In the case of molybdenum and vanadium exemplified as the preferable cocatalyst components above, salts, oxides of these components, or compounds containing these components can be used as the cocatalyst precursor. More specifically, substances such as NH4VO3, (NH4)6Mo7O 24 ·4H2O, Mo(CO)6, and (NH4)MoS4 can be used. When using the substances exemplified above as the precursor, there is an advantage that the loading of the main catalyst component and the cocatalyst component is smooth.

[0053] The solvent of the catalyst solution is not particularly limited as long as it can dissolve the above-mentioned main catalyst precursor and cocatalyst precursor. For example, it is preferable to use water.

[0054] In the method for producing the supported catalyst for producing carbon nanotubes of the present invention, the loading can further include a process of aging for a predetermined time after uniformly mixing the support and the catalyst solution and before firing. Specifically, the mixing can be performed by rotation or stirring at a temperature of 45°C to 80°C. The aging can be performed for 3 minutes to 60 minutes.

[0055] When the catalyst solution is supported on the carrier, it can further include a process of drying before firing. The drying can be carried out at 60°C to 200°C for 4 hours to 16 hours, and the drying method can be an ordinary drying method applied in the industry, such as oven drying, vacuum drying, freeze drying, etc.

[0056] The intermediate produced by the above series of processes is obtained as a supported catalyst for carbon nanotube production through the subsequent final firing step. The firing can be carried out at a temperature of 500°C to 800°C, preferably 600°C to 800°C. When firing is carried out within such a temperature range, most of the main catalyst precursor and the cocatalyst precursor can be converted into the main catalyst component and the cocatalyst component.

[0057] The supported catalyst produced by the above production method can produce a supported catalyst in which the main catalyst component and the cocatalyst component of the catalyst solution are coated on the surface and pores of the carrier. Due to the characteristic particle size distribution of the carrier, the coated active components can act in an almost effective amount, with excellent activity, and thus an improvement in the production yield of carbon nanotubes can be expected.

[0058] Method for producing carbon nanotubes According to another embodiment of the present invention, a method for producing carbon nanotubes using the above catalyst is provided. Specifically, the present invention provides a method for producing carbon nanotubes including the steps of injecting the supported catalyst for carbon nanotube production described above into a fluidized bed reactor, and supplying a carbon source gas and a fluidizing gas to the fluidized bed reactor to react to produce carbon nanotubes.

[0059] The supported catalyst for carbon nanotube production according to an embodiment of the present invention can be injected into a fluidized bed reactor, and further, a carbon source gas and a fluidizing gas can be supplied to the fluidized bed reactor to produce carbon nanotubes.

[0060] The carbon source gas is a carbon-containing gas that can be decomposed at a high temperature to form carbon nanotubes. As specific examples, various carbon-containing compounds such as aliphatic alkanes, aliphatic alkenes, aliphatic alkynes, and aromatic compounds can be used. More specifically, compounds such as methane, ethane, ethylene, acetylene, ethanol, methanol, acetone, carbon monoxide, propane, butane, benzene, cyclohexane, propylene, butene, isobutene, toluene, xylene, cumene, ethylbenzene, naphthalene, phenanthrene, anthracene, acetylene, formaldehyde, and acetaldehyde can be used.

[0061] The fluidizing gas is for imparting fluidity to the carbon nanotubes and catalyst particles synthesized in the fluidized bed reactor. A gas that does not react with the carbon source gas or carbon nanotubes and has high thermal stability can be used. For example, nitrogen gas or an inert gas can be used as the fluidizing gas.

[0062] The fluidized bed reactor can be used without particular limitation as long as it is known to be usable for the production of carbon nanotubes.

[0063] Carbon nanotubes The carbon nanotubes produced by the method for producing carbon nanotubes of the present invention can be bundled carbon nanotubes and can have a number average particle size of 10 to 500 μm, preferably 40 to 300 μm, and particularly preferably 40 to 200 μm.

[0064] The carbon nanotubes can have a bulk density of 10 to 80 kg / m 3 , specifically 20 to 80 kg / m 3 , more specifically 20 to 40 kg / m 3 . Further, the tapped density of the carbon nanotubes can be 15 to 100 kg / m 3 , specifically 30 to 80 kg / m 3 , more specifically 35 to 70 kg / m 3It can be. The carbon nanotubes satisfying the above range are excellent in conductivity, can be excellent in dispersibility while maintaining the initial shape, and are also advantageous for the production of a high-concentration dispersion liquid.

[0065] For the tap density of the carbon nanotubes, a normal tap density measuring instrument can be used. Specifically, it can be measured according to the provisions of ASTM B527-06. For example, it can be measured using TAP-2S manufactured by LOGAN.

[0066] Also, the tap density of the carbon nanotubes can be measured according to the scale of the laboratory. Even when measured according to the scale of the laboratory, results substantially the same as those according to the above provisions can be derived. There can be various methods for measuring according to the scale of the laboratory. For example, first, place a 5 ml cylinder on a scale and zero it, then put 5 ml of carbon nanotubes into the cylinder. After aligning the height of the carbon nanotubes with the scale reading to measure the volume, place it on the scale to measure the weight. After gently tapping the cylinder on the floor about 100 times, read the scale of the cylinder to measure the volume. Then, divide the weight of the carbon nanotubes by the volume of the carbon nanotubes after tapping 100 times, and then the tap density (weight of carbon nanotubes (kg) / volume of carbon nanotubes after tapping 100 times (m 3 )) can be measured.

[0067] The BET specific surface area of the carbon nanotubes can be 150 m 2 / g to 300 m 2 / g, and more specifically can be 160 m 2 / g to 220 m 2 / g. When the above range is satisfied, it can be dispersed at a high concentration. Specifically, in the present invention, the specific surface area of the carbon nanotubes is measured by the BET method. For example, it can be calculated from the nitrogen gas adsorption amount at liquid nitrogen temperature (77K) using BELSORP-mino II manufactured by BEL Japan.

[0068] On the one hand, the average root diameter of the carbon nanotube unit can be 30 nm or less, specifically 10 - 30 nm, and the average length can be 0.5 μm - 200 μm, specifically 10 - 60 μm. When the above range is satisfied, it can be excellent in electrical conductivity and strength, stable at both normal temperature and high temperature, and can also be excellent in dispersibility.

[0069] The carbon nanotube unit is defined by an aspect ratio which is the ratio of the length of the carbon nanotube unit (the length of the major axis passing through the center of the unit) to the diameter (the length of the minor axis passing through the center of the unit and perpendicular to the major axis), and the aspect ratio can be 5 - 50,000, more specifically 10 - 20,000.

[0070] In the present invention, the average strand diameter and length of the carbon nanotube unit can be measured using a field emission scanning electron microscope.

[0071] Examples Hereinafter, in order to specifically explain the present invention, examples and experimental examples will be given for detailed explanation. However, the present invention is not limited by these examples and experimental examples. The examples according to the present invention can be deformed into various other forms, and the scope of the present invention should not be construed as being limited to the examples detailed below. The examples of the present invention are provided to more fully explain the present invention to those with average knowledge in the industry.

[0072] Examples and Comparative Examples As an aluminum-based support precursor, aluminum hydroxide (Al(OH)3) was heat-treated at 450 °C for 4 hours in an air atmosphere to produce an aluminum-based support containing 40 wt% or more of AlO(OH). The produced support was put into a classifier to obtain particles with a number average particle size of 4 μm. Separately, after dissolving NH4VO3 in water, 0.44 mol of citric acid was added per 1 mol of NH4VO3 to produce an aqueous NH4VO3 solution. An aqueous Co(NO3)2·6H2O solution and the aqueous NH4VO3 solution were mixed so that the molar ratio of Co:V was 10:1 to produce a catalyst solution that was a clean aqueous solution.

[0073] The support and the catalyst solution were mixed so that for every 100 mol of Al in the support, there were 16 mol of Co and 1.6 mol of V in the catalyst solution.

[0074] The catalyst solution was supported on the support in a constant-temperature bath at 60 °C for 5 minutes and then dried in an air atmosphere at 120 °C for 6 hours. Next, it was calcined in an air atmosphere at 720 °C for 1.5 hours to produce a supported catalyst, and the content of the active component supported at this time is shown in Table 1 below.

[0075] Also, as shown in Table 1 below, while varying the number average particle size of the support and varying the content of the main catalyst component among the active components, the same procedure as above was carried out to obtain supported catalyst particles for the production of carbon nanotubes in the remaining examples and comparative examples.

[0076] Experimental Example 1. Yield and bulk density of carbon nanotubes Manufacture of Carbon Nanotubes After mounting the produced supported catalyst for the production of carbon nanotubes in the middle part of a cylindrical quartz fluidized bed reactor having a diameter of 55 mm, the temperature was raised to 670 °C in a nitrogen atmosphere and then maintained, and carbon nanotubes were synthesized by reacting for 60 minutes while supplying nitrogen, hydrogen, and ethylene gas at a volume mixing ratio of 1:1:1 at a total of 300 sccm. The yields and bulk densities of the carbon nanotubes synthesized by the supported catalysts of the above examples and comparative examples were measured and are shown in Table 1 below.

[0077] Measurement Method 1) Number average particle size: The number average particle size of the produced support was measured using a particle size analyzer (Microtrac, bluewave).

[0078] 2) Yield: It was calculated by the following formula (1) based on the weight of the supported catalyst used for carbon nanotube production and the weight increase after the reaction.

[0079] [Formula 1] Yield (times) = (Total weight after reaction - Weight of the catalyst used) / Weight of the catalyst used

[0080] 3) Bulk density: After filling a 5 ml container of known weight with powder and measuring the weight, the density was converted by the following formula (2).

[0081] [Formula 2] Bulk density (kg / m 3 ) = Weight of carbon nanotubes (kg) / Volume of carbon nanotubes (m 3 )

[0082] Measurement Results

[0083]

Table 1

[0084] Referring to Table 1 above, in the case of Comparative Examples 1-1, 2-1, 3-1, and 4-1 with a number average particle size of 1.4 μm, it is recognized that the yield and bulk density are at a low level compared to the corresponding examples for each comparative example. It can be understood that this is the result of a decrease in some activity due to a small number average particle size and aggregation between the supported catalyst particles. Also, in the case of Comparative Examples 1-2, 2-2, 3-2, and 4-2 with a number average particle size of the support exceeding 20 μm and being 24 μm, and Comparative Examples 1-3, 2-3, 3-3, and 4-3 with a number average particle size of 50 μm, compared to Examples 1-2, 2-2, 3-2, and 4-2 with a number average particle size of the support of 19 μm which is 20 μm or less, although the size of the catalyst particles increased significantly, the CNT yield was either maintained or rather decreased. This means that when the number average particle size of the support becomes larger than the scope of the present invention, the large particle size of the support instead acts as a factor interfering with the loading of the active component and does not have a favorable effect on the catalytic activity, indicating that within the scope of the number average particle size of the support of the present invention, the loading of the active component is maximized, the use of the catalyst raw material is minimized, and a supported catalyst having the most excellent catalytic activity can be produced.

[0085] Also, when the content of the main catalyst component was increased and supported in the examples, the production yield continued to increase as the content of the supported main catalyst component increased, and as a result, the bulk density also increased. However, in the comparative examples, it was confirmed that the yield did not increase significantly even when the content of the main catalyst component increased, and rather, in certain cases, the yield decreased instead. As described above, this means that within the scope of the number average particle size of the support of the present invention, the loading of the active component can be maximized, whereas in the comparative examples outside the scope of the number average particle size of the support of the present invention, the active component was not uniformly distributed inside the support, and the active component could not play its role as an effective amount.

[0086] Thus, in the case of the supported catalyst according to one embodiment of the present invention, that is, the supported catalyst utilizing a support having a number average particle size of 1.5 to 20 μm, since the active component to be supported acts almost as an active ingredient, the catalytic activity increases, and by preventing the aggregation phenomenon, the loss of activity can be effectively prevented, and it can be confirmed that it can contribute to the improvement of the production yield of carbon nanotubes as it is. It can also be confirmed that such an increase in the effective amount cannot be achieved by increasing the content of the active component, but can be realized when a support having an appropriate particle size distribution is applied.

Claims

1. A carrier having a number average particle size (D ＭＮ ) of 1.5 μm to 20 μm, and an active ingredient supported on the carrier, wherein the active ingredient is composed of a main catalyst component and a promoter component, the main catalyst component is one or more selected from nickel, cobalt, and iron, the promoter component is vanadium, and the carrier is an aluminum-based carrier containing 40% by weight or more of AlO(OH), a supported catalyst for producing carbon nanotubes.

2. The supported catalyst for producing carbon nanotubes according to claim 1, wherein the number average particle size of the carrier is 4.0 μm to 20 μm.

3. The supported catalyst for producing carbon nanotubes according to claim 1 or 2, wherein the number average particle size of the carrier is 4.0 μm to 19 μm.

4. The supported catalyst for producing carbon nanotubes according to any one of claims 1 to 3, wherein the active ingredient is contained in an amount of 5% by weight to 30% by weight based on the total weight of the supported catalyst for producing carbon nanotubes.

5. The supported catalyst for producing carbon nanotubes according to any one of claims 1 to 4, wherein the molar ratio of the promoter component to the main catalyst component is such that the main catalyst component:promoter component is 10:0.1 to 10:

10.

6. The supported catalyst for producing carbon nanotubes according to claim 5, wherein the main catalyst component is cobalt.

7. The supported catalyst for producing carbon nanotubes according to any one of claims 1 to 6, which is used for producing bundled carbon nanotubes.

8. Injecting the supported catalyst for producing carbon nanotubes according to any one of claims 1 to 7 into a fluidized bed reactor; A method for manufacturing carbon nanotubes, comprising the step of supplying a carbon source gas and a fluidizing gas to the fluidized bed reactor and reacting them to produce carbon nanotubes.

9. The method for manufacturing carbon nanotubes according to claim 8, wherein the carbon nanotubes are bundled carbon nanotubes.

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